Lawn mowers employing a blade that rotates about a vertical axis are known as rotary mowers. Rotary mowers may be powered by a gasoline-fueled combustion engine or by an electric motor connected to rotate a shaft to which the cutting blade is attached. For safety reasons, the blade is contained within a downwardly open shroud. The combustion engine or electric motor may also provide power to wheels of the mower to assist on propelling the mower over ground, however a common arrangement on electric powered mowers for residential lawns is for the electric motor to power the rotary blade while the operator pushes the mower along the ground.
Electric motors typically require a motor drive, i.e. an electronic controller, for sensing rotation of the motor's rotor and for driving the motor at a suitable rpm. The motor drive may be embodied by circuitry and components, such as Hall effect sensors, mounted on a circuit board. In order to service the mower, it may be necessary to verify connection of the motor drive to a power source, or to repair or replace the motor drive. In this regard, it is desirable that the motor drive be serviceable without having to remove the entire motor from the shroud.
In some rotary mowers, grass is conveyed through a chute to a collection bag located between the push handle and the shroud. Therefore, if an electric motor is used to power the rotary blade, it is desirable to minimize the space occupied by the motor above the shroud.